"It's not clear that his mixed bag of motley policies would be superior to those of his Democratic opponent," Kristol writes. "He could well pick better Supreme Court justices, which is important; but he could well pursue a less sound foreign policy, which is also important."

"But policy is not the issue," Kristol argues. "Character is. It is clear that Donald Trump does not have the character to be president of the United States. And it is clear Hillary Clinton ought not to be our next president either."

The only alternative is an independent candidate – and Kristol writes it's not too late to recruit one.

"I'm not prone to encouraging or supporting independent candidacies," he said. "I think the two-party system has served America well. I think, all in all, the Republican party has served the country well. … But it was wrong to nominate Donald Trump."

The only states whose ballot access deadlines are before the end of June are Texas and North Carolina, Kristol notes, "and those deadlines are susceptible to legal challenges that are being drawn up as I write."

"Putting together a serious independent campaign is a formidable task—but plenty of operatives and aides and donors and lawyers stand ready," he declared.